Vessel sealer and divider for use with small trocars and cannulas

ABSTRACT

A bipolar forceps for sealing and dividing tissue includes a housing having a shaft affixed thereto. The shaft includes first and second jaw members attached to the distal end thereof which are movable relative to one another from a first spaced apart position to a second position for grasping tissue. At least one of the jaw members includes a knife channel disposed substantially along the length thereof. The knife channel has a depth, a width and an aspect ratio which is defined as the depth of the knife channel divided by the width of the knife channel. Preferably the aspect ratio of the knife channel is at least 1.3. The forceps is connected to a source of electrosurgical energy and also includes an actuator for moving the jaw members relative to one another. A knife assembly is included which allows a user to selectively move a knife to cut tissue disposed between the jaw members.

BACKGROUND

The present disclosure relates to an electrosurgical forceps and moreparticularly, the present disclosure relates to an endoscopic bipolarelectrosurgical forceps for sealing and/or cutting tissue.

TECHNICAL FIELD

Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue. As an alternative toopen forceps for use with open surgical procedures, many modern surgeonsuse endoscopes and endoscopic instruments for remotely accessing organsthrough smaller, puncture-like incisions. As a direct result thereof,patients tend to benefit from less scarring and reduced healing time.

Endoscopic instruments are inserted into the patient through a cannula,or port, which has been made with a trocar. Typical sizes for cannulasrange from three millimeters to twelve millimeters. Smaller cannulas areusually preferred, which, as can be appreciated, ultimately presents adesign challenge to instrument manufacturers who must find ways to makeendoscopic instruments that fit through the smaller cannulas.

Many endoscopic surgical procedures require cutting or ligating bloodvessels or vascular tissue. Due to the inherent spatial considerationsof the surgical cavity, surgeons often have difficulty suturing vesselsor performing other traditional methods of controlling bleeding, e.g.,clamping and/or tying-off transected blood vessels. By utilizing anendoscopic electrosurgical forceps, a surgeon can either cauterize,coagulate/desiccate and/or simply reduce or slow bleeding simply bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied through the jaw members to the tissue. Most small bloodvessels, i.e., in the range below two millimeters in diameter, can oftenbe closed using standard electrosurgical instruments and techniques.However, if a larger vessel is ligated, it may be necessary for thesurgeon to convert the endoscopic procedure into an open-surgicalprocedure and thereby abandon the benefits of endoscopic surgery.Alternatively, the surgeon can seal the larger vessel or tissue.

It is thought that the process of coagulating vessels is fundamentallydifferent than electrosurgical vessel sealing. For the purposes herein,“coagulation” is defined as a process of desiccating tissue wherein thetissue cells are ruptured and dried. “Vessel sealing” or “tissuesealing” is defined as the process of liquefying the collagen in thetissue so that it reforms into a fused mass. Coagulation of smallvessels is sufficient to permanently close them, while larger vesselsneed to be sealed to assure permanent closure.

In order to effectively seal larger vessels (or tissue) two predominantmechanical parameters must be accurately controlled—the pressure appliedto the vessel (tissue) and the gap distance between the electrodes—bothof which are affected by the thickness of the sealed vessel. Moreparticularly, accurate application of pressure is important to opposethe walls of the vessel; to reduce the tissue impedance to a low enoughvalue that allows enough electrosurgical energy through the tissue; toovercome the forces of expansion during tissue heating; and tocontribute to the end tissue thickness which is an indication of a goodseal. It has been determined that a typical fused vessel wall is optimumbetween 0.001 and 0.006 inches. Below this range, the seal may shred ortear and above this range the lumens may not be properly or effectivelysealed.

With respect to smaller vessels, the pressure applied to the tissuetends to become less relevant whereas the gap distance between theelectrically conductive surfaces becomes more significant for effectivesealing. In other words, the chances of the two electrically conductivesurfaces touching during activation increases as vessels become smaller.

Many known instruments include blade members or shearing members whichsimply cut tissue in a mechanical and/or electromechanical manner andare relatively ineffective for vessel sealing purposes. Otherinstruments rely on clamping pressure alone to procure proper sealingthickness and are not designed to take into account gap tolerancesand/or parallelism and flatness requirements which are parameters which,if properly controlled, can assure a consistent and effective tissueseal. For example, it is known that it is difficult to adequatelycontrol thickness of the resulting sealed tissue by controlling clampingpressure alone for either of two reasons: 1) if too much force isapplied, there is a possibility that the two poles will touch and energywill not be transferred through the tissue resulting in an ineffectiveseal; or 2) if too low a force is applied the tissue may pre-maturelymove prior to activation and sealing and/or a thicker, less reliableseal may be created.

As mentioned above, in order to properly and effectively seal largervessels or tissue, a greater closure force between opposing jaw membersis required. It is known that a large closure force between the jawstypically requires a large moment about the pivot for each jaw. Thispresents a design challenge because the jaw members are typicallyaffixed with pins which are positioned to have small moment arms withrespect to the pivot of each jaw member. A large force, coupled with asmall moment arm, is undesirable because the large forces may shear thepins. As a result, designers must compensate for these large closureforces by either designing instruments with metal pins and/or bydesigning instruments which at least partially offload these closureforces to reduce the chances of mechanical failure. As can beappreciated, if metal pivot pins are employed, the metal pins must beinsulated to avoid the pin acting as an alternate current path betweenthe jaw members which may prove detrimental to effective sealing.

Increasing the closure forces between electrodes may have otherundesirable effects, e.g., it may cause the opposing electrodes to comeinto close contact with one another which may result in a short circuitand a small closure force may cause pre-mature movement of the tissueduring compression and prior to activation. As a result thereof,providing an instrument which consistently provides the appropriateclosure force between opposing electrode within a preferred pressurerange will enhance the chances of a successful seal. As can beappreciated, relying on a surgeon to manually provide the appropriateclosure force within the appropriate range on a consistent basis wouldbe difficult and the resultant effectiveness and quality of the seal mayvary. Moreover, the overall success of creating an effective tissue sealis greatly reliant upon the user's expertise, vision, dexterity, andexperience in judging the appropriate closure force to uniformly,consistently and effectively seal the vessel. In other words, thesuccess of the seal would greatly depend upon the ultimate skill of thesurgeon rather than the efficiency of the instrument.

It has been found that the pressure range for assuring a consistent andeffective seal is between about 3 kg/cm² to about 16 kg/cm² and,preferably, within a working range of 7 kg/cm² to 13 kg/cm².Manufacturing an instrument which is capable of providing a closurepressure within this working range has been shown to be effective forsealing arteries, tissues and other vascular bundles.

Various force-actuating assemblies have been developed in the past forproviding the appropriate closure forces to effect vessel sealing. Forexample, one such actuating assembly has been developed by ValleylabInc., a division of Tyco Healthcare LP, for use with Valleylab's vesselsealing and dividing instrument commonly sold under the trademarkLIGASURE ATLAS®. This assembly includes a four-bar mechanical linkage, aspring and a drive assembly which cooperate to consistently provide andmaintain tissue pressures within the above working ranges. The LIGASUREATLAS® is presently designed to fit through a 10 mm cannula and includesa bi-lateral jaw closure mechanism which is activated by a foot switch.A trigger assembly extends a knife distally to separate the tissue alongthe tissue seal. A rotating mechanism is associated with distal end ofthe handle to allow a surgeon to selectively rotate the jaw members tofacilitate grasping tissue. Co-pending U.S. application Ser. Nos.10/179,863 and 10/116,944 and PCT Application Serial Nos. PCT/US01/01890and PCT/7201/11340 describe in detail the operating features of theLIGASURE ATLAS® and various methods relating thereto. The contents ofall of these applications are hereby incorporated by reference herein.

It would be desirous to develop a smaller, simpler endoscopic vesselsealing instrument which can be utilized with a 5 mm cannula.Preferably, the instrument would include a simpler and more mechanicallyadvantageous drive assembly to facilitate grasping and manipulatingvessels and tissue. In addition, it would be desirous to manufacture aninstrument which includes a hand switch and a unilateral jaw closuremechanism. Moreover, it would be advantageous to provide a vesselsealing instrument which effectively, reliably and accurately dividesthe tissue across the tissue seal.

SUMMARY

The present disclosure relates to a bipolar forceps for sealing anddividing tissue which is preferably designed to be utilized with a 5 mmtrocar or cannula and includes a housing and a shaft affixed to thedistal end of the housing. The shaft includes first and second jawmembers attached to the distal end thereof which are movable relative toone another from a first spaced-apart position to a second position forgrasping tissue. At least one of the jaw members includes a knifechannel disposed substantially along the length thereof. The knifechannel has a depth, a width and an aspect ratio which is defined as thedepth of the knife channel divided by the width of the knife channel.

Preferably the aspect ratio of the knife channel is at least 1.3. Theaspect ratio is dependant upon, inter alia, closure pressure, tissuethickness, tissue type, and moisture content of the tissue. For example,in one embodiment according to the present disclosure, the closurepressure is advantageously in the range of abut 7 kg/cm² to about 11kg/cm² which warrants an aspect ratio of about 1.9 to optimize tissuecutting.

The forceps is connected to a source of electrosurgical energy and alsoincludes an actuator for moving the jaw members relative to one another.Advantageously, a knife assembly is included which allows a user toselectively move a knife to cut tissue disposed between the jaw members.The source of electrosurgical energy carries electrical potentials toeach respective jaw member such that the jaw members are capable ofconducting bipolar energy through tissue held therebetween to effect atissue seal.

In one embodiment, the first jaw member and the second jaw member eachinclude includes an elongated slot which run in opposition substantiallyalong the respective lengths thereof such that the two opposingelongated slots form the knife channel for reciprocating the knife todivide tissue disposed between the two jaw members.

In yet another embodiment, at least one of the jaw members includes oneor more non-conductive stop members disposed thereon which controls thedistance between the jaw members when tissue is held therebetween.Advantageously, the stop members maintain a gap distance of about 0.001inches to about 0.006 inches between the jaw members when tissue iscompressed between the jaw members. In still another embodiment, theactuator is selectively lockable to maintain a closure pressure in therange of about 3 kg/cm² to about 16 kg/cm² and, preferably, about 7kg/cm² to about 13 kg/cm² between the jaw members which is advantageousin producing effective and reliable tissue seals.

Advantageously, the forceps includes a unilateral jaw assembly, i.e.,the first jaw member is movable relative to the second jaw member andthe second jaw member is substantially fixed. In another embodiment, theforceps may also include a rotating assembly for rotating the jawmembers about a longitudinal axis defined through the shaft.

Still another embodiment of the present disclosure relates to a bipolarforceps for sealing and dividing tissue which includes a housing havinga shaft affixed thereto having first and second jaw members attached toa distal end thereof. At least one of the jaw members includes a knifechannel disposed substantially along the length of the jaw member. Theforceps also includes an actuator for moving jaw members relative to oneanother from a first position wherein the jaw members are disposed inspaced relation relative to one another to a second position wherein thejaw members cooperate to grasp tissue therebetween. The forceps isconnected to a source of electrosurgical energy connected to each jawmember such that the jaw members are capable of conducting bipolarenergy through tissue held therebetween to effect a tissue seal.

Advantageously, a knife assembly is included which has an elongatedknife bar for supporting a knife with a leading cutting edge. Theelongated knife bar is selectively moveable within the knife channel toforce tissue disposed within the knife channel into engagement with thecutting edge of the knife upon distal movement thereof which, in turn,cuts tissue disposed between the jaw members. Preferably, the elongatedknife bar includes a chamfered edge which directs tissue from the knifechannel and towards the cutting edge of the knife. As can beappreciated, having the leading edge of the knife bar chamfered insuresaccurate and effective tissue separation.

A rotating assembly may also be included for rotating the jaw membersabout the longitudinal axis defined through the shaft. Preferably, therotating assembly is located near the proximal end of the housing andnear the hand switch to facilitate rotation.

Advantageously, the movable jaw member includes a first electricalpotential and the fixed jaw member includes a second electricalpotential. A lead connects the movable jaw member to the first potentialand a conductive tube (which is disposed through the shaft) conducts asecond electrical potential to the fixed jaw member. Preferably, theconductive tube is connected to the rotating assembly to permitselective rotation of the jaw members.

In still yet another embodiment, a spring is included with the driveassembly to facilitate actuation of the movable handle and to assure theclosure force is maintained within a working range of about 3 kg/cm² toabout 16 kg/cm². At least one of the jaw members may include a series ofstop members disposed thereon for regulating the distance between thejaw members (i.e., creating a gap between the two opposing jaw members)during the sealing process.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a left, perspective view of an endoscopic bipolar forcepsshowing a housing, a shaft and an end effector assembly according to thepresent disclosure;

FIG. 2 is a top view of the forceps of FIG. 1;

FIG. 3 is a left, side view of the forceps of FIG. 1;

FIG. 4 is a left, perspective view of the forceps of FIG. 1 showing therotation of the end effector assembly about a longitudinal axis “A”;

FIG. 5 is a front view of the forceps of FIG. 1;

FIG. 6 is an enlarged view of the indicated area of detail of FIG. 5showing an enhanced view of the end effector assembly detailing a pairof opposing jaw members;

FIG. 7 is an enlarged, rear perspective view of the housing;

FIG. 8 is an enlarged, left perspective view of the end effectorassembly with the jaw members shown in open configuration;

FIG. 9 is an enlarged, side view of the end effector assembly;

FIG. 10 is an enlarged, perspective view of the underside of the upperjaw member of the end effector assembly;

FIG. 11 is an enlarged, broken perspective view showing the end effectorassembly and highlighting a cam-like closing mechanism which cooperateswith a reciprocating pull sleeve to move the jaw members relative to oneanother;

FIG. 12 is a full perspective view of the end effector assembly of FIG.11;

FIG. 13 is an enlarged, perspective view of the housing and the internalworking components thereof;

FIG. 14 is top, perspective view of the housing of FIG. 13 with partsseparated;

FIG. 15 is a left, perspective view of a rotating assembly, driveassembly, knife assembly and lower jaw member according to the presentdisclosure;

FIG. 16 is a rear, perspective view of the rotating assembly, driveassembly and knife assembly;

FIG. 17 is an enlarged, top, perspective view of the end effectorassembly with parts separated;

FIG. 18 is an enlarged, perspective view of the knife assembly;

FIG. 19 is an enlarged, perspective view of the rotating assembly;

FIG. 20 is an enlarged, perspective view of the drive assembly;

FIG. 21 is an enlarged, perspective view of the knife assembly withparts separated;

FIG. 22 is an enlarged view of the indicated area of detail of FIG. 21;

FIG. 23 is a greatly-enlarged, perspective view of a distal end of theknife assembly;

FIG. 24 is a greatly-enlarged, perspective view of a knife drive of theknife assembly;

FIG. 25 is an enlarged, perspective view of the rotating assembly andlower jaw member with parts separated;

FIG. 26 is a cross section of the area indicated in detail in FIG. 25;

FIG. 27 is a greatly-enlarged, perspective view of the lower jaw member;

FIG. 28 is an enlarged, perspective view of the drive assembly;

FIG. 29 is an enlarged perspective view of the drive assembly of FIG. 28with parts separated;

FIG. 30 is an internal, side view of the housing showing theinner-working components thereof;

FIG. 31 is a cross-section of the housing with the end effector shown inopen configuration and showing the internal, electrical routing of anelectrosurgical cable and electrical leads;

FIG. 32 is a greatly-enlarged view of the indicated area of detail ofFIG. 31;

FIG. 33 is a greatly-enlarged view of the indicated area of detail ofFIG. 31;

FIG. 34 is a greatly-enlarged, cross section of the shaft taken alongline 34-34;

FIG. 35 is a side, cross section of the shaft and end effector assembly;

FIG. 36 is a perspective view showing the forceps of the presentdisclosure being utilized with a 5 mm cannula;

FIG. 37 is a side, cross section of the housing showing the movingcomponents of the drive assembly during actuation;

FIG. 38 is a greatly-enlarged, perspective view of a handle lockingmechanism for use with the drive assembly;

FIG. 39 is a greatly-enlarged view of the indicated area of detail inFIG. 37;

FIG. 40 is a greatly-enlarged view of the indicated area of detail inFIG. 37;

FIG. 41 is an enlarged, rear, perspective view of the end effectorsshown grasping tissue;

FIG. 42 is an enlarged view of a tissue seal;

FIG. 43 is a side, cross section of a tissue seal;

FIG. 44 is a cross section of the housing with the handle in a lockedconfiguration and showing the moving components of the knife assemblyduring activation;

FIG. 45 is an enlarged view of the area indicated in detail in FIG. 44;

FIG. 46 is a side, cross section of a tissue seal after separation bythe knife assembly;

FIG. 47 is a side, cross section of the housing showing the release ofthe knife assembly and release of the drive assembly to open the jawmembers and release the tissue;

FIG. 48 is a greatly-enlarged view of the indicated area of detail inFIG. 47;

FIG. 49 is a greatly-enlarged view of the indicated area of detail inFIG. 47;

FIG. 50 is a greatly-enlarged schematic diagram of an upper knifechannel of the movable jaw member showing one preferred configuration tofacilitate tissue separation;

FIG. 51 is a greatly-enlarged end cross section showing the knife beingsupported by a knife bar which rides within a lower knife channeldisposed in the fixed jaw member; and

FIG. 52 is a greatly-enlarged schematic view of a knife which isspring-biased to expand fully within the knife channel uponreciprocation of the knife assembly.

DETAILED DESCRIPTION

Turning now to FIGS. 1-3, one embodiment of an endoscopic bipolarforceps 10 is shown for use with various surgical procedures andgenerally includes a housing 20, a handle assembly 30, a rotatingassembly 80, a trigger assembly 70 and an end effector assembly 100which mutually cooperate to grasp, seal and divide tubular vessels andvascular tissue 420 (FIG. 36). Although the majority of the figuredrawings depict a bipolar forceps 10 for use in connection withendoscopic surgical procedures, the present disclosure may be used formore traditional open surgical procedures. For the purposes herein, theforceps 10 is described in terms of an endoscopic instrument, however,it is contemplated that an open version of the forceps may also includethe same or similar operating components and features as describedbelow.

Forceps 10 includes a shaft 12 which has a distal end 16 dimensioned tomechanically engage the end effector assembly 100 and a proximal end 14which mechanically engages the housing 20. Details of how the shaft 12connects to the end effector are described in more detail below withrespect to FIG. 25. The proximal end 14 of shaft 12 is received withinthe housing 20 and the connections relating thereto are described indetail below with respect to FIGS. 13 and 14. In the drawings and in thedescriptions which follow, the term “proximal”, as is traditional, willrefer to the end of the forceps 10 which is closer to the user, whilethe term “distal” will refer to the end which is further from the user.

As best seen in FIG. 1, forceps 10 also includes an electrosurgicalcable 310 which connects the forceps 10 to a source of electrosurgicalenergy, e.g., a generator (not shown). Preferably, generators such asthose sold by Valleylab—a division of Tyco Healthcare LP, located inBoulder Colo. are used as a source of electrosurgical energy, e.g.,FORCE EZ™ Electrosurgical Generator, FORCE FX™ ElectrosurgicalGenerator, FORCE 1C™, FORCE 2™ Generator, SurgiStat™ II. One such systemis described in commonly-owned U.S. Pat. No. 6,033,399 entitled“ELECTROSURGICAL GENERATOR WITH ADAPTIVE POWER CONTROL” the entirecontents of which are hereby incorporated by reference herein. Othersystems have been described in commonly-owned U.S. Pat. No. 6,187,003entitled “BIPOLAR ELECTROSURGICAL INSTRUMENT FOR SEALING VESSELS” theentire contents of which is also incorporated by reference herein.

Preferably, the generator includes various safety and performancefeatures including isolated output, independent activation ofaccessories. Preferably, the electrosurgical generator includesValleylab's Instant Response™ technology features which provides anadvanced feedback system to sense changes in tissue 200 times per secondand adjust voltage and current to maintain appropriate power. TheInstant Response™ technology is believed to provide one or more of thefollowing benefits to surgical procedure:

-   -   Consistent clinical effect through all tissue types;    -   Reduced thermal spread and risk of collateral tissue damage;    -   Less need to “turn up the generator”; and    -   Designed for the minimally invasive environment.

Cable 310 is internally divided into cable lead 310 a, 310 b and 310 cwhich each transmit electrosurgical energy through their respective feedpaths through the forceps 10 to the end effector assembly 100 asexplained in more detail below with respect to FIGS. 14 and 30.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50 as explained in more detail belowwith respect to the operation of the forceps 10. Rotating assembly 80 ispreferably integrally associated with the housing 20 and is rotatableapproximately 180 degrees in either direction about a longitudinal axis“A” (See FIG. 4). Details of the rotating assembly 80 are described inmore detail with respect to FIGS. 13, 14, 15 and 16

As best seen in FIGS. 2, 13 and 14, housing 20 is formed from two (2)housing halves 20 a and 20 b which each include a plurality ofinterfaces 27 a-27 f which are dimensioned to mechanically align andengage one another to form housing 20 and enclose the internal workingcomponents of forceps 10. As can be appreciated, fixed handle 50 which,as mentioned above, is integrally associated with housing 20, takesshape upon the assembly of the housing halves 20 a and 20 b.

It is envisioned that a plurality of additional interfaces (not shown)may disposed at various points around the periphery of housing halves 20a and 20 b for ultrasonic welding purposes, e.g., energydirection/deflection points. It is also contemplated that housing halves20 a and 20 b (as well as the other components described below) may beassembled together in any fashion known in the art. For example,alignment pins, snap-like interfaces, tongue and groove interfaces,locking tabs, adhesive ports, etc. may all be utilized either alone orin combination for assembly purposes.

Rotating assembly 80 includes two halves 82 a and 82 b which, whenassembled, form the rotating assembly 80 which, in turn, houses thedrive assembly 150 and the knife assembly 140 (See FIGS. 13, 14 and 25).Half 80 a includes a series of detents/flanges 375 a, 375 b, 375 c and375 d (FIG. 25) which are dimensioned to engage a pair of correspondingsockets or other mechanical interfaces (not shown) disposed withinrotating half 80 a. Movable handle 40 and trigger assembly 70 arepreferably of unitary construction and are operatively connected to thehousing 20 and the fixed handle 50 during the assembly process.

As mentioned above, end effector assembly 100 is attached at the distalend 14 of shaft 12 and includes a pair of opposing jaw members 110 and120. Movable handle 40 of handle assembly 30 is ultimately connected toa drive assembly 150 which, together, mechanically cooperate to impartmovement of the jaw members 110 and 120 from an open position whereinthe jaw members 110 and 120 are disposed in spaced relation relative toone another, to a clamping or closed position wherein the jaw members110 and 120 cooperate to grasp tissue 420 (FIG. 36) therebetween.

It is envisioned that the forceps 10 may be designed such that it isfully or partially disposable depending upon a particular purpose or toachieve a particular result. For example, end effector assembly 100 maybe selectively and releasably engageable with the distal end 16 of theshaft 12 and/or the proximal end 14 of shaft 12 may be selectively andreleasably engageable with the housing 20 and the handle assembly 30. Ineither of these two instances, the forceps 10 would be considered“partially disposable” or “reposable”, i.e., a new or different endeffector assembly 100 (or end effector assembly 100 and shaft 12)selectively replaces the old end effector assembly 100 as needed. As canbe appreciated, the presently disclosed electrical connections wouldhave to be altered to modify the instrument to a reposable forceps.

Turning now to the more detailed features of the present disclosure asdescribed with respect to FIGS. 1-14, movable handle 40 includes afinger loop 41 which has an aperture 42 defined therethrough whichenables a user to grasp and move the handle 40 relative to the fixedhandle 50. Handle 40 also includes an ergonomically-enhanced grippingelement 43 disposed along the inner peripheral edge of aperture 42 whichis designed to facilitate gripping of the movable handle 40 duringactivation. It is envisioned that gripping element 43 may include one ormore protuberances, scallops and/or ribs to enhance gripping. As bestseen in FIG. 14, movable handle 40 is selectively moveable about a pairof pivot pins 29 a and 29 b from a first position relative to fixedhandle 50 to a second position in closer proximity to the fixed handle50 which, as explained below, imparts movement of the jaw members 110and 120 relative to one another. The movable handle include a clevis 45which forms a pair of upper flanges 45 a and 45 b each having anaperture 49 a and 49 b, respectively, at an upper end thereof forreceiving the pivot pins 29 a and 29 b therethrough and mounting theupper end of the handle 40 to the housing 20. In turn, each pin 29 a and29 b mounts to a respective housing half 20 a and 20 b.

Each upper flange 45 a and 45 b also includes a force-actuating flangeor drive flange 47 a and 47 b, respectively, which are aligned alonglongitudinal axis “A” and which abut the drive assembly 150 such thatpivotal movement of the handle 40 forces actuating flange against thedrive assembly 150 which, in turn, closes the jaw members 110 and 120.For the purposes herein, 47 a and 47 b which act simultaneously on thedrive assembly are referred to as “driving flange 47”. A more detailedexplanation of the inter-cooperating components of the handle assembly30 and the drive assembly 150 is discussed below.

As best seen in FIG. 14, the lower end of the movable handle 40 includesa flange 90 which is preferably mounted to the movable handle 40 by pins94 a and 94 b which engage a corresponding pair of apertures 91 a and 91b disposed within the lower portion of handle 40 and apertures 97 a and97 b disposed within flange 90, respectively. Other methods ofengagement are also contemplated, snap-lock, spring tab, etc. Flange 90also includes a t-shaped distal end 95 which rides within a predefinedchannel 51 disposed within fixed handle 50 to lock the movable handle 40relative to the fixed handle 50. Additional features with respect to thet-shaped end 95 are explained below in the detailed discussion of theoperational features of the forceps 10.

Movable handle 40 is designed to provide a distinct mechanical advantageover conventional handle assemblies due to the unique position of thepivot pins 29 a and 29 b (i.e., pivot point) relative to thelongitudinal axis “A” of the shaft 12 and the disposition of the drivingflange 47 along longitudinal axis “A”. In other words, it is envisionedthat by positioning the pivot pins 29 a and 29 b above the drivingflange 47, the user gains lever-like mechanical advantage to actuate thejaw members 110 and 120 enabling the user to close the jaw members 110and 120 with lesser force while still generating the required forcesnecessary to effect a proper and effective tissue seal. It is alsoenvisioned that the unilateral design of the end effector assembly 100will also increase mechanical advantage as explained in more detailbelow.

As shown best in FIGS. 6-12, the end effector assembly 100 includesopposing jaw members 110 and 120 which cooperate to effectively grasptissue 420 for sealing purposes. The end effector assembly 100 isdesigned as a unilateral assembly, i.e., jaw member 120 is fixedrelative to the shaft 12 and jaw member 110 pivots about a pivot pin 103to grasp tissue 420.

More particularly, the unilateral end effector assembly 100 includes onestationary or fixed jaw member 120 mounted in fixed relation to theshaft 12 and pivoting jaw member 110 mounted about a pivot pin 103attached to the stationary jaw member 120. A reciprocating sleeve 60 isslidingly disposed within the shaft 12 and is remotely operable by thedrive assembly 150. The pivoting jaw member 110 includes a detent orprotrusion 117 which extends from jaw member 110 through an aperture 62disposed within the reciprocating sleeve 60 (FIG. 12). The pivoting jawmember 110 is actuated by sliding the sleeve 60 axially within the shaft12 such that a distal end 63 of the aperture 62 abuts against the detent117 on the pivoting jaw member 110 (See FIGS. 11 and 12). Pulling thesleeve 60 proximally closes the jaw members 110 and 120 about tissue 420grasped therebetween and pushing the sleeve 60 distally opens the jawmembers 110 and 120 for grasping purposes.

As best illustrated in FIGS. 8 and 10, a knife channel 115 a and 115 bruns through the center of the jaw members 110 and 120, respectively,such that a blade 185 from the knife assembly 140 can cut the tissue 420grasped between the jaw members 110 and 120 when the jaw members 110 and120 are in a closed position. More particularly, the blade 185 can onlybe advanced through the tissue 420 when the jaw members 110 and 120 areclosed thus preventing accidental or premature activation of the blade185 through the tissue 420. Put simply, the knife channel 115 (made upof half channels 115 a and 115 b) is blocked when the jaws members 110and 120 are opened and aligned for distal activation when the jawmembers 110 and 120 are closed (See FIGS. 35 and 39). It is alsoenvisioned that the unilateral end effector assembly 100 may bestructured such that electrical energy can be routed through the sleeve60 at the protrusion 117 contact point with the sleeve 60 or using a“brush” or lever (not shown) to contact the back of the moving jawmember 110 when the jaw member 110 closes. In this instance, theelectrical energy would be routed through the protrusion 117 to thestationary jaw member 120. Alternatively, the cable lead 311 may berouted to energize the stationary jaw member 120 and the otherelectrical potential may be conducted through the sleeve 60 andtransferred to the pivoting jaw member 110 which establishes electricalcontinuity upon retraction of the sleeve 60. It is envisioned that thisparticular envisioned embodiment will provide at least two importantsafety features: 1) the blade 185 cannot extend while the jaw members110 and 120 are opened; and 2) electrical continuity to the jaw members110 and 120 is made only when the jaw members are closed. Theillustrated forceps 10 only includes the novel knife channel 115.

As best shown in FIG. 8, jaw member 110 also includes a jaw housing 116which has an insulative substrate or insulator 114 and an electricallyconducive surface 112. Insulator 114 is preferably dimensioned tosecurely engage the electrically conductive sealing surface 112. Thismay be accomplished by stamping, by overmolding, by overmolding astamped electrically conductive sealing plate and/or by overmolding ametal injection molded seal plate. For example and as shown in FIG. 17,the electrically conductive sealing plate 112 includes a series ofupwardly extending flanges 111 a and 111 b which are designed tomatingly engage the insulator 114. The insulator 114 includes ashoe-like interface 107 disposed at a distal end thereof which isdimensioned to engage the outer periphery 116 a of the housing 116 in aslip-fit manner. The shoe-like interface 107 may also be overmoldedabout the outer periphery of the jaw 110 during a manufacturing step. Itis envisioned that lead 311 terminates within the shoe-like interface107 at the point where lead 311 electrically connects to the seal plate112 (not shown). The movable jaw member 110 also includes a wire channel113 which is designed to guide cable lead 311 into electrical continuitywith sealing plate 112 as described in more detail below.

All of these manufacturing techniques produce jaw member 110 having anelectrically conductive surface 112 which is substantially surrounded byan insulating substrate 114. The insulator 114, electrically conductivesealing surface 112 and the outer, non-conductive jaw housing 116 arepreferably dimensioned to limit and/or reduce many of the knownundesirable effects related to tissue sealing, e.g., flashover, thermalspread and stray current dissipation. Alternatively, it is alsoenvisioned that the jaw members 110 and 120 may be manufactured from aceramic-like material and the electrically conductive surface(s) 112 arecoated onto the ceramic-like jaw members 110 and 120.

Jaw member 110 includes a pivot flange 118 which includes protrusion117. Protrusion 117 extends from pivot flange 118 and includes anarcuately-shaped inner surface 111 dimensioned to matingly engage theaperture 62 of sleeve 60 upon retraction thereof. Pivot flange 118 alsoincludes a pin slot 119 which is dimensioned to engage pivot pin 103 toallow jaw member 110 to rotate relative to jaw member 120 uponretraction of the reciprocating sleeve 60. As explained in more detailbelow, pivot pin 103 also mounts to the stationary jaw member 120through a pair of apertures 101 a and 101 b disposed within a proximalportion of the jaw member 120.

It is envisioned that the electrically conductive sealing surface 112may also include an outer peripheral edge which has a pre-defined radiusand the insulator 114 meets the electrically conductive sealing surface112 along an adjoining edge of the sealing surface 112 in a generallytangential position. Preferably, at the interface, the electricallyconductive surface 112 is raised relative to the insulator 114. Theseand other envisioned embodiments are discussed in co-pending, commonlyassigned Application Serial No. PCT/US01/11412 entitled “ELECTROSURGICALINSTRUMENT WHICH REDUCES COLLATERAL DAMAGE TO ADJACENT TISSUE” byJohnson et al. and co-pending, commonly assigned Application Serial No.PCT/US01/11411 entitled “ELECTROSURGICAL INSTRUMENT WHICH IS DESIGNED TOREDUCE THE INCIDENCE OF FLASHOVER” by Johnson et al.

Preferably, the electrically conductive surface 112 and the insulator114, when assembled, form a longitudinally-oriented slot 115 a definedtherethrough for reciprocation of the knife blade 185. It is envisionedthat the knife channel 115 a cooperates with a corresponding knifechannel 115 b defined in stationary jaw member 120 to facilitatelongitudinal extension of the knife blade 185 along a preferred cuttingplane to effectively and accurately separate the tissue 420 along theformed tissue seal 450 (See FIGS. 42 and 46).

Jaw member 120 includes similar elements to jaw member 110 such as jawhousing 126 having an insulator 124 and an electrically conductivesealing surface 122 which is dimensioned to securely engage theinsulator 124. Likewise, the electrically conductive surface 122 and theinsulator 124, when assembled, include a longitudinally-oriented channel115 a defined therethrough for reciprocation of the knife blade 185. Asmentioned above, when the jaw members 110 and 120 are closed abouttissue 420, knife channels 115 a and 115 b form a complete knife channel115 to allow longitudinal extension of the knife 185 in a distal fashionto sever tissue 420 along the tissue seal 450. It is also envisionedthat the knife channel 115 may be completely disposed in one of the twojaw members, e.g., jaw member 120, depending upon a particular purpose.It is envisioned that the fixed jaw member 120 may be assembled in asimilar manner as described above with respect to jaw member 110.

As best seen in FIG. 8, jaw member 120 includes a series of stop members750 preferably disposed on the inner facing surfaces of the electricallyconductive sealing surface 122 to facilitate gripping and manipulationof tissue and to define a gap “G” (FIG. 24) between opposing jaw members110 and 120 during sealing and cutting of tissue. It is envisioned thatthe series of stop members 750 may be employed on one or both jawmembers 110 and 120 depending upon a particular purpose or to achieve adesired result. A detailed discussion of these and other envisioned stopmembers 750 as well as various manufacturing and assembling processesfor attaching and/or affixing the stop members 750 to the electricallyconductive sealing surfaces 112, 122 are described in commonly-assigned,co-pending U.S. Application Serial No. PCT/US01/11413 entitled “VESSELSEALER AND DIVIDER WITH NON-CONDUCTIVE STOP MEMBERS” by Dycus et al.which is hereby incorporated by reference in its entirety herein.

Jaw member 120 is designed to be fixed to the end of a rotating tube 160which is part of the rotating assembly 80 such that rotation of the tube160 will impart rotation to the end effector assembly 100 (See FIGS. 25and 27). Jaw member 120 includes a rear C-shaped cuff 170 having a slot177 defined therein which is dimensioned to receive a slide pin 171.More particularly, slide pin 171 includes a slide rail 176 which extendssubstantially the length thereof which is dimensioned to slide intofriction-fit engagement within slot 177. A pair of chamfered plates 172a and 172 b extend generally radially from the slide rail 176 andinclude a radius which is substantially the same radius as the outerperiphery of the rotating tube 160 such that the shaft 12 can encompasseach of the same upon assembly.

As explained in more detail below, fixed jaw member 120 is connected toa second electrical potential through tube 160 which is connected at itsproximal end to lead 310 c. More particularly, fixed jaw 120 is weldedto the rotating tube 160 and includes a fuse clip, spring clip or otherelectro-mechanical connection which provides electrical continuity tothe fixed jaw member 120 from lead 310 c (See FIG. 32). As best shown inFIGS. 25 and 26, the rotating tube 160 includes an elongated guide slot167 disposed in an upper portion thereof which is dimensioned to carrylead 311 therealong. The chamfered plates 172 a and 172 b also form awire channel 175 which is dimensioned to guide the cable lead 311 fromthe tube 160 and into the movable jaw member 110 (See FIG. 8). Lead 311carries a first electrical potential to movable jaw 110. As explained inmore detail below with respect to the internal electrical connections ofthe forceps, a second electrical connection from lead 310 c is conductedthrough the tube 160 to the fixed jaw member 120.

As shown in FIG. 25, the distal end of the tube 160 is generallyC-shaped to include two upwardly extending flanges 162 a and 162 b whichdefine a cavity 165 for receiving the proximal end of the fixed jawmember 120 inclusive of C-shaped cuff 170 and slide pin 171 (See FIG.27). Preferably, the tube cavity 165 retains and secures the jaw member120 in a friction-fit manner, however, the jaw member 120 may be weldedto the tube 160 depending upon a particular purpose. Tube 160 alsoincludes an inner cavity 169 defined therethrough which reciprocates theknife assembly 140 upon distal activation thereof and an elongated guiderail 163 which guides the knife assembly 140 during distal activation.The details with respect to the knife assembly are explained in moredetail with respect to FIGS. 21-24. The proximal end of tube 160includes a laterally oriented slot 168 which is designed to interfacewith the rotating assembly 80 as described below.

FIG. 25 also shows the rotating assembly 80 which includes C-shapedrotating halves 82 a and 82 b which, when assembled about tube 160, forma generally circular rotating member 82. More particularly, eachrotating half, e.g., 82 b, includes a series of mechanical interfaces375 a, 375 b, 375 c and 375 d which matingly engage a correspondingseries of mechanical interfaces in half 82 a to form rotating member 82.Half 82 b also includes a tab 89 b which together with a correspondingtab 89 a disposed on half 82 a (phantomly illustrated) cooperate tomatingly engage slot 168 disposed on tube 160. As can be appreciated,this permits selective rotation of the tube 160 about axis “A” bymanipulating the rotating member 82 in the direction of the arrow “B”(see FIG. 4).

As best shown in the exploded view of FIG. 17, jaw members 110 and 120are pivotably mounted with respect to one another such that jaw member110 pivots in a unilateral fashion from a first open position to asecond closed position for grasping and manipulating tissue 420. Moreparticularly, fixed jaw member 120 includes a pair of proximal, upwardlyextending flanges 125 a and 125 b which define a cavity 121 dimensionedto receive flange 118 of movable jaw member 110 therein. Each of theflanges 125 a and 125 b includes an aperture 101 a and 101 b,respectively, defined therethrough which secures pivot pin 103 onopposite sides of pivot mount 119 disposed within jaw member 110. Asexplained in detail below with respect to the operation of the jawmembers 110 and 120, proximal movement of the tube 60 engages detent 117to pivot the jaw member 110 to a closed position.

FIGS. 13 and 14 show the details of the housing 20 and the componentfeatures thereof, namely, the drive assembly 150, the rotating assembly80, the knife assembly 140, the trigger assembly 70 and the handles 40and 50. More particularly, FIG. 13 shows the above-identified assembliesand components in an assembled form in the housing 20 and FIG. 14 showsan exploded view of each of the above-identified assemblies andcomponents.

As shown best in FIG. 14, the housing includes halves 20 a and 20 bwhich, when mated, form housing 20. As can be appreciated, housing 20,once formed, houses the various assemblies identified above which willenable a user to selectively manipulate, grasp, seal and sever tissue420 in a simple, effective, and efficient manner. Preferably, each halfof the housing, e.g., half 20 b, includes a series of mechanicalinterfacing component, e.g., 27 a-27 f which align and/or mate with acorresponding series of mechanical interfaces (not shown) to align thetwo housing halves 20 a and 20 b about the inner components andassemblies. The housing halves 20 a and 20 b are then preferably sonicwelded to secure the housing halves 20 a and 20 b once assembled.

As mentioned above, the movable handle 40 includes clevis 45 which formsupper flanges 45 a and 45 b which pivot about pins 29 a and 29 b to pullthe reciprocating sleeve 60 along longitudinal axis “A” and force duringflange 47 against the drive assembly 150 which, in turn, closes the jawmembers 110 and 120. As mentioned above, the lower end of the movablehandle 40 includes a flange 90 which has a t-shaped distal end 95 whichrides within a predefined channel 51 disposed within fixed handle 50 tolock the movable handle 40 in a preset orientation relative to the fixedhandle 50. The arrangement of the upper flanges 45 a and 45 b and thepivot point of the movable handle 40 provides a distinct mechanicaladvantage over conventional handle assemblies due to the unique positionof the pivot pins 29 a and 29 b (i.e., pivot point) relative to thelongitudinal axis “A” of the driving flange 47. In other words, bypositioning the pivot pins 29 a and 29 b above the driving flange 47,the user gains lever-like mechanical advantage to actuate the jawmembers 110 and 120. This reduces the overall amount of mechanical forcenecessary to close the jaw members 110 and 120 to effect a tissue seal.

Handle 40 also includes a finger loop 41 which defines opening 42 whichis dimensioned to facilitate grasping the handle 40. Preferably, fingerloop 41 includes rubber insert 43 which enhances the overall ergonomic“feel” of the handle member 40. A locking flange 44 is disposed on theouter periphery of the handle member 40 above the finger loop 41.Locking flange 44 prevents the trigger assembly 70 from firing when thehandle member 40 is oriented in a non-actuated position, i.e., the jawmembers 110 and 120 are open. As can be appreciated, this preventsaccidental or premature severing of tissue 420 prior to completion ofthe tissue seal 450.

Fixed handle 50 includes halves 50 a and 50 b which, when assembled,form handle 50. Fixed handle 50 includes a channel 51 defined thereinwhich is dimensioned to receive flange 90 in a proximal moving mannerwhen movable handle 40 is actuated. The t-shaped free end 95 of handle40 is dimensioned for facile reception within channel 51 of handle 50.It is envisioned that flange 90 may be dimensioned to allow a user toselectively, progressively and/or incrementally move jaw members 110 and120 relative to one another from the open to closed positions. Forexample, it is also contemplated that flange 90 may include aratchet-like interface which lockingly engages the movable handle 40and, therefore, jaw members 110 and 120 at selective, incrementalpositions relative to one another depending upon a particular purpose.Other mechanisms may also be employed to control and/or limit themovement of handle 40 relative to handle 50 (and jaw members 110 and120) such as, e.g., hydraulic, semi-hydraulic, linear actuator(s),gas-assisted mechanisms and/or gearing systems.

As best illustrated in FIG. 13, housing halves 20 a and 20 b whenassembled form an internal cavity 52 which predefines the channel 51within fixed handle 50 such that an entrance pathway 54 and an exitpathway 58 are formed for reciprocation of the t-shaped flange end 95therein. When assembled, two generally triangular-shaped members 57 (onedisposed in each handle half 50 a and 50 b) are positioned in closeabutment relative to one another to define a rail or track 192therebetween. During movement of the flange 90 along the entrance andexit pathways 54 and 58, respectively, the t-shaped end 95 rides alongtrack 192 between the two triangular members 57 according to theparticular dimensions of the triangularly-shaped members 57, which, ascan be appreciated, predetermines part of the overall pivoting motion ofhandle 40 relative to fixed handle 50.

Once actuated, handle 40 moves in a generally arcuate fashion towardsfixed handle 50 about pivot pins 29 a and 29 b which forces drivingflange 47 proximally against the drive assembly 150 which, in turn,pulls reciprocating sleeve 60 in a generally proximal direction to closejaw member 110 relative to jaw member 120. Moreover, proximal rotationof the handle 40 causes the locking flange 44 to release, i.e.,“unlock”, the trigger assembly 70 for selective actuation. This featureis shown in detail with reference to FIGS. 33, 37 and 44 and theexplanation of the operation of the knife assembly 70 explained below.

The operating features and relative movements of the internal workingcomponents of the forceps 10 are shown by phantom representation in thevarious figures. As mentioned above, when the forceps 10 is assembled apredefined channel 52 is formed within the fixed handle 50. The channelincludes entrance pathway 51 and an exit pathway 58 for reciprocation ofthe flange 90 and the t-shaped end 95 therein. Once assembled, the twogenerally triangular-shaped members 57 are positioned in close abutmentrelative to one another and define track 192 disposed therebetween.

As the handle 40 is squeezed and flange 90 is incorporated into channel51 of fixed handle 50, the driving flange 47, through the mechanicaladvantage of the above-the-center pivot points, biases flange 154 ofdrive ring 159 which, in turn, compresses a spring 67 against a rearring 156 of the drive assembly 150 (FIG. 40). As a result thereof, therear ring 156 reciprocates sleeve 60 proximally which, in turn, closesjaw member 110 onto jaw member 120. It is envisioned that theutilization of an over-the-center pivoting mechanism will enable theuser to selectively compress the coil spring 67 a specific distancewhich, in turn, imparts a specific pulling load on the reciprocatingsleeve 60 which is converted to a rotational torque about the jaw pivotpin 103. As a result, a specific closure force can be transmitted to theopposing jaw members 110 and 120.

FIGS. 37 and 38 show the initial actuation of handle 40 towards fixedhandle 50 which causes the free end 95 of flange 90 to move generallyproximally and upwardly along entrance pathway 51. During movement ofthe flange 90 along the entrance and exit pathways 51 and 58,respectively, the t-shaped end 95 rides along track 192 between the twotriangular members 57. Once the desired position for the sealing site isdetermined and the jaw members 110 and 120 are properly positioned,handle 40 may be compressed fully such that the t-shaped end 95 offlange 90 clears a predefined rail edge 193 located atop thetriangular-shaped members 57. Once end 95 clears edge 193, releasingmovement of the handle 40 and flange 90 is redirected into a catch basin194 located at the proximal end of the triangular member 57. Moreparticularly, upon a slight reduction in the closing pressure of handle40 against handle 50, the handle 40 returns slightly distally towardsentrance pathway 51 but is re-directed towards exit pathway 58. At thispoint, the release or return pressure between the handles 40 and 50which is attributable and directly proportional to the release pressureassociated with the compression of the drive assembly 150 causes the end95 of flange 90 to settle or lock within catch basin 194. Handle 40 isnow secured in position within fixed handle 50 which, in turn, locks thejaw members 110 and 120 in a closed position against the tissue 420.

As mentioned above, the jaw members 110 and 120 may be opened, closedand rotated to manipulate tissue 420 until sealing is desired. Thisenables the user to position and re-position the forceps 10 prior toactivation and sealing. As illustrated in FIG. 4, the end effectorassembly 100 is rotatable about longitudinal axis “A” through rotationof the rotating assembly 80. As explained in more detail below, it isenvisioned that the unique feed path of the cable lead 311 through therotating assembly 80, along shaft 12 and, ultimately, to the jaw member110 enables the user to rotate the end effector assembly 100 about 180degrees in both the clockwise and counterclockwise direction withouttangling or causing undue strain on cable lead 311. Cable lead 310 c isfused or clipped to the proximal end of tube 160 and is generallyunaffected by rotation of the jaw members 110 and 120. As can beappreciated, this facilitates the grasping and manipulation of tissue420.

Again as best shown in FIGS. 13 and 14, trigger assembly 70 mounts atopmovable handle 40 and cooperates with the knife assembly 140 toselectively translate knife 185 through a tissue seal 450. Moreparticularly, the trigger assembly 70 includes a finger actuator 71 anda U-shaped upwardly-extending flange 74 having legs 74 a and 74 b. Apivot pin 73 mounts the trigger assembly 70 between housing halves 20 aand 20 b for selective rotation thereof. A pair of safety tabs 76 a and76 b are disposed atop finger actuator 71 and are dimensioned to abutthe locking flange 44 on handle 40 when the handle 40 is disposed in anon-actuated position, i.e., the jaw members 110 and 120 are opened.

As best seen in FIG. 14, the legs 74 a and 74 b of the U-shaped flange74 each include a respective slot 77 a and 77 b defined therein whichare each dimensioned to receive a free end of an elongated drive bar 75.Drive bar 75, in turn, is dimensioned to sit within a drive slot 147which is part of the knife assembly 140 explained in detail below. Thetrigger assembly 70 is mounted atop the donut-like drive ring 141 of theknife assembly 140. Proximal activation of the finger actuator 71rotates the trigger assembly 70 about pivot pin 73 which, in turn,forces the drive bar 75 distally, which, as explained in more detailbelow, ultimately extends the knife 185 through the tissue 420. A spring350 biases the knife assembly 70 in a retracted position such that aftersevering tissue 420 the knife 185 and the knife assembly 70 areautomatically returned to a pre-firing position.

As mentioned above, the locking flange 44 abuts tabs 76 a and 76 b whenthe handle 40 is disposed in a non-actuated position. When the handle 40is actuated and flange 90 is fully reciprocated within channel 51 of thefixed handle 50, the locking flange 44 moves proximally allowingactivation of the trigger assembly 70 (See FIGS. 37 and 44).

Drive assembly 150 includes reciprocating sleeve 60, drive housing 158,spring 67, drive ring 159, drive stop 155 and guide sleeve 157 which allcooperate to form the drive assembly 150. More particularly and as bestshown in FIGS. 28 and 29, the reciprocating sleeve 60 includes a distalend 65 which as mentioned above has an aperture 62 formed therein foractuating the detent 117 of jaw member 110. The distal end 65 preferablyincludes a scoop-like support member 69 for supporting the proximal endof the fixed jaw member 120 therein. The proximal end 61 of thereciprocating sleeve 60 includes a slot 68 defined therein which isdimensioned to slidingly support the knife assembly 70 for longitudinalreciprocation thereof to sever tissue 420. The slot 68 also permitsretraction of the reciprocating sleeve 60 over the knife assembly 140during the closing of jaw member 110 relative to jaw member 120.

The proximal end 61 of the reciprocating sleeve 60 is positioned withinan aperture 151 in drive housing 158 to permit selective reciprocationthereof upon actuation of the movable handle 40. The spring 67 isassembled atop the drive housing 158 between a rear stop 156 of thedrive housing 158 and a forward stop 154 of the drive ring 159 such thatmovement of the forward stop 154 compresses the spring 67 against therear stop 156 which, in turn, reciprocates the drive sleeve 60. As aresult thereof, the jaw members 110 and 120 and the movable handle 40are biased by spring 67 in an open configuration. The drive stop 155 isfixedly positioned atop the drive housing 158 and biases the upperflanges 45 a and 45 b of the movable handle 40 when actuated such thatthe driving flange 47 forces the stop 154 of the drive ring 159proximally against the force of the spring 67. The spring 67, in turn,forces the rear stop 156 proximally to reciprocate the sleeve 60 (SeeFIG. 40). Preferably, the rotating assembly 80 is located proximate thedriving flange 47 to facilitate rotation of the end effector assembly100. The guide sleeve 157 mates with the proximal end 61 of thereciprocating sleeve 60 and affixes to the drive housing 158. Theassembled drive assembly 150 is shown best in FIG. 20.

As best shown in FIGS. 18 and 21-24, the knife assembly 140 includes anelongated rod 182 having a bifurcated distal end comprising prongs 182 aand 182 b which cooperate to receive a knife bar 184 therein. The knifeassembly 180 also includes a proximal end 183 which is keyed tofacilitate insertion into tube 160 of the rotating assembly 80. A knifewheel 148 is secured to the knife bar 182 by a pin 143. Moreparticularly, the elongated knife rod 182 includes apertures 181 a and181 b which are dimensioned to receive and secure the knife wheel 148 tothe knife rod 182 such that longitudinal reciprocation of the knifewheel 148, in turn, moves the elongated knife rod 182 to sever tissue420.

The knife wheel 148 is preferably donut-like and includes rings 141 aand 141 b which define a drive slot 147 designed to receive the drivebar 75 of the trigger assembly 70 such that proximal actuation of thetrigger assembly 70 forces the drive bar 75 and the knife wheel 148distally. It is envisioned that aperture 181 a may be used for aparticular trigger assembly 70 configuration and aperture 181 b may beused for a different trigger assembly 70 configuration. As such, pin 143is designed for attachment through either aperture 181 a or 181 b tomount the knife wheel 148 (See FIG. 24). Knife wheel 148 also includes aseries of radial flanges 142 a and 142 b which are dimensioned to slidealong both channel 163 of tube 160 and slot 68 of the reciprocatingsleeve 60 (See FIG. 15).

As mentioned above, the knife rod 182 is dimensioned to mount the knifebar 184 between prongs 182 a and 182 b preferably in friction-fitengagement. The knife bar 184 includes a series of steps 186 a, 186 band 186 c which reduce the profile of the knife bar 184 towards thedistal end thereof. The distal ends of the knife bar 184 includes aknife support 188 which is dimensioned to retain knife blade 185. It isenvisioned that the knife blade 185 may be welded to the knife support188 of secured in any manner known in the trade.

As best shown in the exploded view of the FIGS. 14 and 30-32, theelectrical leads 310 a, 310 b, 310 c and 311 are fed through the housing20 by electrosurgical cable 310. More particularly, the electrosurgicalcable 310 is fed into the bottom of the housing 20 through fixed handle50. Lead 310 c extends directly from cable 310 into the rotatingassembly 80 and connects (via a fused clip or spring clip or the like)to tube 60 to conduct the second electrical potential to fixed jawmember 120. Leads 310 a and 310 b extend from cable 310 and connect tothe hand switch or joy-stick-like toggle switch 200.

Switch 200 includes an ergonomically dimensioned toggle plate 205 havinga pair of wings 207 a and 207 b which preferably conform to the outershape of housing 20 (once assembled). It is envisioned that the switch200 permits the user to selectively activate the forceps 10 in a varietyof different orientations, i.e., multi-oriented activation. As can beappreciated, this simplifies activation. A pair of prongs 204 a and 204b extend distally and mate with a corresponding pair of mechanicalinterfaces 21 a and 21 b disposed within housing 20 (See FIG. 32).Prongs 204 a and 204 b preferably snap-fit to the housing 20 duringassembly. Toggle plate 205 also includes a switch interface 203 withmates with a switch button 202 which, in turn, connects to electricalinterface 201. The electrical leads 310 a and 310 b are electricallyconnected to electrical interface 201. When the toggle plate 205 isdepressed, trigger lead 311 carries the first electrical potential tojaw member 110. More particularly, lead 311 extends from interface 201through a plurality of slots 84 a, 84 b and 84 c of the rotatingassembly 80 (See FIGS. 25 and 30) and along the upper portion of tube160 and eventually connects to the movable jaw member 110 as describedabove (See FIGS. 32, 34 and 35).

When the switch 200 is depressed, electrosurgical energy is transferredthrough leads 311 and 310 c to jaw members 110 and 120, respectively. Itis envisioned that a safety switch or circuit (not shown) may beemployed such that the switch cannot fire unless the jaw members 110 and120 are closed and/or unless the jaw members 110 and 120 have tissue 420held therebetween. In the latter instance, a sensor (not shown) may beemployed to determine if tissue 420 is held therebetween. In addition,other sensor mechanisms may be employed which determine pre-surgical,concurrent surgical (i.e., during surgery) and/or post surgicalconditions. The sensor mechanisms may also be utilized with aclosed-loop feedback system coupled to the electrosurgical generator toregulate the electrosurgical energy based upon one or more pre-surgical,concurrent surgical or post surgical conditions. Various sensormechanisms and feedback systems are described in commonly-owned,co-pending U.S. patent application Ser. No. 10/427,832 entitled “METHODAND SYSTEM FOR CONTROLLING OUTPUT OF RF MEDICAL GENERATOR” filed on May1, 2003 the entire contents of which are hereby incorporated byreference herein.

Preferably, the jaw members 110 and 120 are electrically isolated fromone another such that electrosurgical energy can be effectivelytransferred through the tissue 420 to form seal 450. For example and asbest illustrated in FIGS. 32, 34 and 35, each jaw member, e.g., 110,includes a uniquely-designed electrosurgical cable path disposedtherethrough which transmits electrosurgical energy to the electricallyconductive sealing surface 112. It is envisioned that jaw member 110 mayinclude one or more cable guides or crimp-like electrical connectors todirect cable lead 311 towards electrically conductive sealing surface112. Preferably, cable lead 311 is held loosely but securely along thecable path to permit rotation of the jaw member 110 about pivot 103. Ascan be appreciated, this isolates electrically conductive sealingsurface 112 from the remaining operative components of the end effectorassembly 100, jaw member 120 and shaft 12. As explained in detail above,the second electrical potential is conducted to jaw member 120 throughtube 160. The two potentials are isolated from one another by virtue ofthe insulative sheathing surrounding cable lead 311.

It is contemplated that utilizing a cable feed path for cable lead 311and by utilizing a conductive tube 160 to carry the first and secondelectrical potentials not only electrically isolates each jaw member 110and 120 but also allows the jaw members 110 and 120 to pivot about pivotpin 103 without unduly straining or possibly tangling cable lead 311.Moreover, it is envisioned that the simplicity of the electricalconnections greatly facilitates the manufacturing and assembly processand assures a consistent and tight electrical connection for thetransfer of energy through the tissue 420.

As mentioned above, it is envisioned that cable leads 311 and 310 c arefed through respective halves 82 a and 82 b of the rotating assembly 80in such a manner to allow rotation of the shaft 12 (via rotation of therotating assembly 80) in the clockwise or counter-clockwise directionwithout unduly tangling or twisting the cable leads 311 and 310 c. Moreparticularly, each cable lead 311 and 310 c is fed through a series ofconjoining slots 84 a, 84 b, 84 c and 84 d located in the two halves 82a and 82 b of the rotating assembly 80. Preferably each conjoining pairof slots, e.g., 84 a, 84 b and 84 c, 84 d, are large enough to permitrotation of the rotating assembly 80 without unduly straining ortangling the cable leads 311 and 310 c. The presently disclosed cablelead feed path is envisioned to allow rotation of the rotation assemblyapproximately 180 degrees in either direction.

Turning back to FIG. 14 which shows the exploded view of the housing 20,rotating assembly 80, trigger assembly 70, movable handle 40 and fixedhandle 50, it is envisioned that all of these various component partsalong with the shaft 12 and the end effector assembly 100 are assembledduring the manufacturing process to form a partially and/or fullydisposable forceps 10. For example and as mentioned above, the shaft 12and/or end effector assembly 100 may be disposable and, therefore,selectively/releasably engagable with the housing 20 and rotatingassembly 80 to form a partially disposable forceps 10 and/or the entireforceps 10 may be disposable after use.

As best seen in FIG. 13, once assembled, spring 67 is poised forcompression atop drive housing 158 upon actuation of the movable handle40. More particularly, movement of the handle 40 about pivot pins 29 aand 29 b reciprocates the flange 90 into fixed handle 50 and forcesdrive flange 47 against flange 154 of drive ring 159 to compress spring67 against the rear stop 156 to reciprocate the sleeve 60 (See FIG. 40).

Preferably, the trigger assembly 70 is initially prevented from firingby the locking flange 44 disposed on movable handle 40 which abutsagainst the trigger assembly 70 prior to actuation. It is envisionedthat the opposing jaw members 110 and 120 may be rotated and partiallyopened and closed without unlocking the trigger assembly 70 which, ascan be appreciated, allows the user to grip and manipulate the tissue420 without premature activation of the knife assembly 140. As mentionedbelow, only when the t-shaped end 95 of flange 90 is completelyreciprocated within channel 51 of the fixed handle 50 and seated withinpre-defined catch basin 194 will the locking flange allow activation ofthe trigger assembly 70. The operating features and relative movementsof these internal working components of the forceps 10 are shown byphantom representation and directional arrows and are best illustratedin FIGS. 36-49.

FIG. 36 shows the forceps approximating tissue. As the handle 40 issqueezed and flange 90 is incorporated into channel 54 of fixed handle50, the drive flange 47, through the mechanical advantage of the overthe center pivot pins 29 a and 29 b is rotated generally proximally tocompress spring 67. Simultaneously, the reciprocating sleeve 60 ispulled proximally by the movement of rear ring 156 which, in turn,causes aperture 62 of sleeve 60 to proximally cam detent 117 and closethe jaw member 110 relative to jaw member 120 (See FIGS. 37-40).

It is envisioned that the mechanical advantage of the over-the-centerpivot will enable the user to selectively compress the coil spring 67 aspecific distance which, in turn, imparts a specific load on thereciprocating sleeve 60. The reciprocating sleeve's 60 load is convertedto a torque about the jaw pivot 103. As a result, a specific closureforce can be transmitted to the opposing jaw members 110 and 120. Asmentioned above, the jaw members 110 and 120 may be opened, closed androtated to manipulate tissue 420 until sealing is desired withoutunlocking the trigger assembly 70. This enables the user to position andre-position the forceps 10 prior to activation and sealing. Moreparticularly, as illustrated in FIG. 4, the end effector assembly 100 isrotatable about longitudinal axis “A” through rotation of the rotatingassembly 80.

Once the desired position for the sealing site is determined and the jawmembers 110 and 120 are properly positioned, handle 40 may be compressedfully such that the t-shaped end 95 of flange 90 clears a predefinedrail edge 193 located atop the triangular-shaped members 57. Once end 95clears edge 193, the end is directed into catch basin 194 located withinthe exit pathway 58. More particularly, upon a slight reduction in theclosing pressure of handle 40 against handle 50, the handle 40 returnsslightly distally towards entrance pathway 54 but is re-directed towardsexit pathway 58 into catch basin 194 (See FIG. 38). At this point, therelease or return pressure between the handles 40 and 50 which isattributable and directly proportional to the release pressureassociated with the compression of the drive assembly 150 causes the end95 of flange 90 to settle or lock within catch basin 194. Handle 40 isnow secured in position within fixed handle 50 which, in turn, locks thejaw members 110 and 120 in a closed position against the tissue 420.

At this point the jaws members 110 and 120 are fully compressed aboutthe tissue 420 (FIG. 26). Moreover, the forceps 10 is now ready forselective application of electrosurgical energy and subsequentseparation of the tissue 420, i.e., as t-shaped end 95 seats withincatch basin 194, locking flange 44 moves into a position to permitactivation of the trigger assembly 70 (FIGS. 44 and 45).

As the t-shaped end 95 of flange 90 becomes seated within catch basin194, a proportional axial force on the reciprocating sleeve 60 ismaintained which, in turn, maintains a compressive force betweenopposing jaw members 110 and 120 against the tissue 420. It isenvisioned that the end effector assembly 100 and/or the jaw members 110and 120 may be dimensioned to off-load some of the excessive clampingforces to prevent mechanical failure of certain internal operatingelements of the end effector 100.

As can be appreciated, the combination of the mechanical advantage ofthe over-the-center pivot along with the compressive force associatedwith the compression spring 67 facilitate and assure consistent, uniformand accurate closure pressure about the tissue 420 within the desiredworking pressure range of about 3 kg/cm² to about 16 kg/cm² and,preferably about 7 kg/cm² to about 13 kg/cm². By controlling theintensity, frequency and duration of the electrosurgical energy appliedto the tissue 420, the user can either cauterize, coagulate/desiccate,seal and/or simply reduce or slow bleeding. As mentioned above, twomechanical factors play an important role in determining the resultingthickness of the sealed tissue and effectiveness of the seal 450, i.e.,the pressure applied between opposing jaw members 110 and 120 and thegap distance “G” between the opposing sealing surfaces 112, 122 of thejaw members 110 and 120 during the sealing process. However, thicknessof the resulting tissue seal 450 cannot be adequately controlled byforce alone. In other words, too much force and the two jaw members 110and 120 would touch and possibly short resulting in little energytraveling through the tissue 420 thus resulting in a bad tissue seal450. Too little force and the seal 450 would be too thick.

Applying the correct force is also important for other reasons: tooppose the walls of the vessel; to reduce the tissue impedance to a lowenough value that allows enough current through the tissue 420; and toovercome the forces of expansion during tissue heating in addition tocontributing towards creating the required end tissue thickness which isan indication of a good seal 450.

Preferably, the electrically conductive sealing surfaces 112, 122 of thejaw members 110, 120, respectively, are relatively flat to avoid currentconcentrations at sharp edges and to avoid arcing between high points.In addition and due to the reaction force of the tissue 420 whenengaged, jaw members 110 and 120 are preferably manufactured to resistbending. For example, the jaw members 110 and 120 may be tapered alongthe width thereof which is advantageous for two reasons: 1) the taperwill apply constant pressure for a constant tissue thickness atparallel; 2) the thicker proximal portion of the jaw members 110 and 120will resist bending due to the reaction force of the tissue 420.

As mentioned above, at least one jaw member, e.g., 120, may include astop member 750 which limits the movement of the two opposing jawmembers 110 and 120 relative to one another. Preferably, the stop member750 extends from the sealing surface 122 a predetermined distanceaccording to the specific material properties (e.g., compressivestrength, thermal expansion, etc.) to yield a consistent and accurategap distance “G” during sealing (FIG. 41). Preferably, the gap distancebetween opposing sealing surfaces 112 and 122 during sealing ranges fromabout 0.001 inches to about 0.006 inches and, more preferably, betweenabout 0.002 and about 0.003 inches. Preferably, the non-conductive stopmembers 750 are molded onto the jaw members 110 and 120 (e.g.,overmolding, injection molding, etc.), stamped onto the jaw members 110and 120 or deposited (e.g., deposition) onto the jaw members 110 and120. For example, one technique involves thermally spraying a ceramicmaterial onto the surface of the jaw member 110 and 120 to form the stopmembers 750. Several thermal spraying techniques are contemplated whichinvolve depositing a broad range of heat resistant and insulativematerials on various surfaces to create stop members 750 for controllingthe gap distance between electrically conductive surfaces 112 and 122.

As energy is being selectively transferred to the end effector assembly100, across the jaw members 110 and 120 and through the tissue 420, atissue seal 450 forms isolating two tissue halves 420 a and 420 b. Atthis point and with other known vessel sealing instruments, the usermust remove and replace the forceps 10 with a cutting instrument (notshown) to divide the tissue halves 420 a and 420 b along the tissue seal450. As can be appreciated, this is both time consuming and tedious andmay result in inaccurate tissue division across the tissue seal 450 dueto misalignment or misplacement of the cutting instrument along theideal tissue cutting plane.

As explained in detail above, the present disclosure incorporates knifeassembly 140 which, when activated via the trigger assembly 70,progressively and selectively divides the tissue 420 along an idealtissue plane in precise manner to effectively and reliably divide thetissue 420 into two sealed halves 420 a and 420 b (See FIG. 46) with atissue gap 475 therebetween. The knife assembly 140 allows the user toquickly separate the tissue 420 immediately after sealing withoutsubstituting a cutting instrument through a cannula or trocar port. Ascan be appreciated, accurate sealing and dividing of tissue 420 isaccomplished with the same forceps 10.

It is envisioned that knife blade 185 may also be coupled to the same oran alternative electrosurgical energy source to facilitate separation ofthe tissue 420 along the tissue seal 450 (Not shown). Moreover, it isenvisioned that the angle of the knife blade tip 185 may be dimensionedto provide more or less aggressive cutting angles depending upon aparticular purpose. For example, the knife blade 185 may be positionedat an angle which reduces “tissue wisps” associated with cutting. Moreover, the knife blade 185 may be designed having different bladegeometries such as serrated, notched, perforated, hollow, concave,convex etc. depending upon a particular purpose or to achieve aparticular result.

Once the tissue 420 is divided into tissue halves 420 a and 420 b, thejaw members 110 and 120 may be opened by re-grasping the handle 40 asexplained below. It is envisioned that the knife assembly 140 generallycuts in a progressive, uni-directional fashion (i.e., distally).

As best shown in FIGS. 47-49, re-initiation or re-grasping of the handle40 again moves t-shaped end 95 of flange 90 generally proximally alongexit pathway 58 until end 95 clears a lip 196 disposed atoptriangular-shaped members 57 along exit pathway 58. Once lip 196 issufficiently cleared, handle 40 and flange 90 are fully and freelyreleasable from handle 50 along exit pathway 58 upon the reduction ofgrasping/gripping pressure which, in turn, returns the jaw members 110and 120 to the open, pre-activated position.

In one embodiment according to the present disclosure, the knife channel115 a disposed within the movable jaw member 110 includes a specificaspect ratio (depth or height “h” divided by width “w”−“h”/“w”) tofacilitate and enhance tissue separation. It has been discovered thatseveral factors affect the ideal aspect ratio for cutting tissue for theknife channel 115 a and include: tissue type, tissue thickness, tissuedesiccation, closure pressure, jaw size and blade configuration. Ingeneral, higher jaw pressure, softer tissue, thicker tissue and tissuewith higher water content all tend to contribute to the need for ahigher aspect ratio.

More particularly and as best shown in FIG. 50, one or both of the jawmembers 110 and 120 may be designed to have a specific aspect ratiowhich controls the influx of and shape of tissue within the knifechannel 115 a when tissue 420 is clamped between jaw members 110 and120. As can be appreciated, since the length of the cutting edge of theknife 185 is substantially the same depth or height “h” of the knifechannel 115 a, the likelihood that the knife 185 will “miss” cuttingacross the entire tissue seal 450 is substantially reduced when thetissue does not bulge completely into the knife channel 115 a. Since thetissue 420 is prevented from bulging completely into the knife channel,all of the tissue remains in the cutting path of the knife (See FIG.50).

Preferably, the aspect ratio of the knife channel 115 a (and/or 115 b ifapplicable) is about 1.3 or higher. In one embodiment, the knife channel115 a is approximately 0.012 inches wide and 0.023 inches high (or deep)yielding an aspect ratio of about 1.9. It is envisioned that an aspectratio of about 1.9 is ideal for closure forces within the range of about7 kg/cm² to about 11 kg/cm² between the jaw members 110 and 120. As canbe appreciated, the ideal aspect ratio may change for closure pressuresoutside the above working ranges or depending upon tissue type,thickness and moisture level.

FIG. 51 shows yet another embodiment of the present disclosure whereinthe knife bar 184 rides within the knife channel 115 b of fixed jaw 120.It is envisioned that the knife bar 184 which supports the knife 185thereon, forces tissue 420 out of the channel 115 b and into engagementwith the knife 185 during distal movement of the knife bar 184.Preferably, the knife bar 184 includes a chamfer 188 a on the leadingedge thereof which is designed to force the tissue 420 over the knifebar 184 and into the cutting path of the knife 185 (See FIG. 21). In oneembodiment, the knife bar 184 is designed to extend from the leadingedge of the knife 185 (e.g., within about 0.010 inches to about 0.100inches) to ensure that the tissue 420 is lifted from the knife channel115 b in advance of the cutting edge of the knife 185. In this instance,less emphasis is placed on the overall aspect ratio of the knife channel115 b.

It is envisioned that the opposing knife channels 115 a and 115 b mayhave the same or different configurations or, alternatively, onechannel, e.g., 115 a, may be configured to have a specific aspect ratiowhile the other channel, e.g., 115 b, may be dimensioned to house theknife bar 184 as described above.

In another embodiment according to the present disclosure, the knife 285may be automatically adjustable depending upon the tissue thickness suchthat the knife 285 expands fully within the depths of the knife channel115 a, 115 b upon reciprocation thereof. More particularly, it iscontemplated that the knife 285 may include two halves 286 a and 286 bwhich are spring-biased in an open configuration to expand from aminimum height “h1” to a maximum height “h2” and any positiontherebetween depending upon the tissue thickness, tissue type, closurepressure, etc. (See FIG. 52). In other words, the knife 285 is designedto ride fully within the knife channel 115 a, 115 b irrespective of thetissue parameters. As can be appreciated, upon distal movement thereof,the configuration or height of the knife 285 changes to expand fullywithin the knife channel 115 a, 115 b to reliably cut across the entiretissue seal 450. It is also envisioned that this particularconfiguration will produce reliable and consistent tissue divisionshould the jaw members 110 and 120 bulge, skew or become slightlyoff-parallel.

As best seen in FIG. 52, the knife 285 include two halves 286 a and 286b which are biased towards the open configuration by a spring 287. It isenvisioned that the halves 286 a and 286 b may be adjacent one anotheror telescopically disposed within one another to expand within the knifechannel 115 a and 115 b upon distal movement of the knife bar 184. Theupper and lower tips 289 a and 289 b of the halves 286 a and 286 b maybe dimensioned to slide against the inner periphery of the upper andlower knife channels 115 a and 115 b to facilitate reciprocation, e.g.,blunt edges, Teflon coated, etc. Alternatively, the halves 286 a and 286b may be biased about a pivot (not shown) to accomplish a similarpurpose, i.e., ride fully along the knife channel 115 a and 115 b.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, it may be preferable to add other features tothe forceps 10, e.g., an articulating assembly to axially displace theend effector assembly 100 relative to the elongated shaft 12.

It is also contemplated that the forceps 10 (and/or the electrosurgicalgenerator used in connection with the forceps 10) may include a sensoror feedback mechanism (not shown) which automatically selects theappropriate amount of electrosurgical energy to effectively seal theparticularly-sized tissue grasped between the jaw members 110 and 120.The sensor or feedback mechanism may also measure the impedance acrossthe tissue during sealing and provide an indicator (visual and/oraudible) that an effective seal has been created between the jaw members110 and 120. Examples of such sensor systems are described incommonly-owned U.S. patent application Ser. No. 10/427,832 entitled“METHOD AND SYSTEM FOR CONTROLLING OUTPUT OF RF MEDICAL GENERATOR” filedon May 1, 2003 the entire contents of which are hereby incorporated byreference herein.

Moreover, it is contemplated that the trigger assembly 70 may includeother types of recoil mechanism which are designed to accomplish thesame purpose, e.g., gas-actuated recoil, electrically-actuated recoil(i.e., solenoid), etc. It is also envisioned that the forceps 10 may beused to cut tissue 420 without sealing. Alternatively, the knifeassembly 70 may be coupled to the same or alternate electrosurgicalenergy source to facilitate cutting of the tissue 420.

Although the figures depict the forceps 10 manipulating an isolatedvessel 420, it is contemplated that the forceps 10 may be used withnon-isolated vessels as well. Other cutting mechanisms are alsocontemplated to cut tissue 420 along the ideal tissue plane.

It is envisioned that the outer surface of the end effector assembly 100may include a nickel-based material, coating, stamping, metal injectionmolding which is designed to reduce adhesion between the jaw members 110and 120 with the surrounding tissue during activation and sealing.Moreover, it is also contemplated that the conductive surfaces 112 and122 of the jaw members 110 and 120 may be manufactured from one (or acombination of one or more) of the following materials: nickel-chrome,chromium nitride, MedCoat 2000 manufactured by The ElectrolizingCorporation of OHIO, inconel 600 and tin-nickel. The tissue conductivesurfaces 112 and 122 may also be coated with one or more of the abovematerials to achieve the same result, i.e., a “non-stick surface”. Ascan be appreciated, reducing the amount that the tissue “sticks” duringsealing improves the overall efficacy of the instrument.

One particular class of materials disclosed herein has demonstratedsuperior non-stick properties and, in some instances, superior sealquality. For example, nitride coatings which include, but not are notlimited to: TiN, ZrN, TiAlN, and CrN are preferred materials used fornon-stick purposes. CrN has been found to be particularly useful fornon-stick purposes due to its overall surface properties and optimalperformance. Other classes of materials have also been found to reducingoverall sticking. For example, high nickel/chrome alloys with a Ni/Crratio of approximately 5:1 have been found to significantly reducesticking in bipolar instrumentation. One particularly useful non-stickmaterial in this class is Inconel 600. Bipolar instrumentation havingsealing surfaces 112 and 122 made from or coated with Ni200, Ni201(˜100% Ni) also showed improved non-stick performance over typicalbipolar stainless steel electrodes.

As can be appreciated, locating the switch 200 on the forceps 10 hasmany advantages. For example, the switch 200 reduces the amount ofelectrical cable in the operating room and eliminates the possibility ofactivating the wrong instrument during a surgical procedure due to“line-of-sight” activation. Moreover, decommissioning the switch 200when the trigger is actuated eliminates unintentionally activating thedevice during the cutting process. It is also envisioned that the switch200 may be disposed on another part of the forceps 10, e.g., the fixedhandle 40, rotating assembly 80, housing 20, etc.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1. A bipolar forceps for sealing and dividing tissue, comprising: ahousing having a shaft affixed thereto, the shaft including first andsecond jaw members attached to a distal end thereof, the jaw membersadapted to connect to a source of electrosurgical energy such that thejaw members are capable of conducting bipolar energy through tissue heldtherebetween to effect a tissue seal; an actuator operable to move thejaw members relative to one another from a first position wherein thejaw members are disposed in spaced relation relative to one another to asecond position wherein the jaw members cooperate to grasp tissuetherebetween, the actuator being operable to maintain a closure pressurein the range of about 7 kg/cm² to about 11 kg/cm² between the jawmembers; at least one of the jaw members including a knife channeldefined substantially along the length thereof, the knife channelincluding a depth, a width and an aspect ratio wherein the aspect ratiois defined as the depth of the knife channel divided by the width of theknife channel, the aspect ratio being about 1.9 such that the knifechannel controls the influx of tissue therein to partially fill theknife channel under the closure pressure of about 7 kg/cm² to about 11kg/cm² to facilitate cutting tissue; and a knife assembly that isselectively moveable within the knife channel to cut tissue disposedbetween the jaw members, the knife assembly including: a knife bladehaving a leading edge; and a knife bar configured to extend from theleading edge of the knife blade and configured to ride in the knifechannel, the knife bar ensuring that tissue is lifted from the knifechannel in advance of the leading edge of the knife blade.
 2. A bipolarforceps for sealing and dividing tissue according to claim 1, wherein atleast one of the jaw members includes at least one non-conductive stopmember disposed thereon which controls the distance between the jawmembers when tissue is held therebetween.
 3. A bipolar forceps forsealing and dividing tissue according to claim 1, wherein the actuatoris selectively lockable to maintain the closure pressure in the range ofabout 7 kg/cm² to about 11 kg/cm² between the jaw members.
 4. A bipolarforceps for sealing and dividing tissue according to claim 1, whereinthe first jaw member is movable relative to the second jaw member andthe second jaw member is substantially fixed.
 5. A bipolar forceps forsealing and dividing tissue according to claim 1, further comprising arotating assembly for rotating the jaw members about a longitudinal axisdefined through the shaft.
 6. The bipolar forceps according to claim 1,wherein the knife bar is configured to extend from the leading edge ofthe knife blade by a distance of about 0.010 inches to about 0.100inches (about 0.254 millimeters to about 2.54 millimeters).
 7. A bipolarforceps for sealing and dividing tissue, comprising: a housing having ashaft affixed thereto, the shaft including first and second jaw membersattached to a distal end thereof, the jaw members adapted to connect toa source of electrosurgical energy such that the jaw members are capableof conducting bipolar energy through tissue held therebetween to effecta tissue seal; an actuator operable to move the jaw members relative toone another from a first position wherein the jaw members are disposedin spaced relation relative to one another to a second position whereinthe jaw members cooperate to grasp tissue therebetween, the actuatorbeing operable to maintain a closure pressure in the range of about 7kg/cm² to about 11 kg/cm² between the jaw members, the first jaw memberincluding a knife channel defined substantially along the lengththereof, the knife channel including a depth, a width and an aspectratio wherein the aspect ratio is defined as the depth of the knifechannel divided by the width of the knife channel, the aspect ratiobeing about 1.9 such that the knife channel controls the influx oftissue therein to partially fill the knife channel under the closurepressure of about 7 kg/cm² to about 11 kg/cm² to facilitate cuttingtissue, the second jaw member including a knife channel definedsubstantially along the length thereof; and a knife assembly that isselectively moveable within the knife channel of the second jaw memberto cut tissue disposed between the jaw members, the knife assemblyincluding: a knife blade having a leading edge; and a knife barconfigured to extend from the leading edge of the knife blade andconfigured to ride in the knife channel, the knife bar ensuring thattissue is lifted from the knife channel in advance of the leading edgeof the knife blade.
 8. The bipolar forceps according to claim 7, whereinthe knife bar is configured to extend from the leading edge of the knifeblade by a distance of about 0.010 inches to about 0.100 inches (about0.254 millimeters to about 2.54 millimeters).